Photoluminescence Properties and Energy Transfer in Eu2+-Yb2+Codoped SrSi2O2N2Oxynitride Phosphor

Eu 2+ -Yb 2+ codoped SrSi 2 O 2 N 2 phosphors were prepared and their photoluminescence properties were investigated in comparison with the single Eu 2+ -doped and the single Yb 2+ -doped samples. Their photoluminescence properties were investigated as the factors of Yb 2+ ion concentration, excitation wavelength, and temperature. Compared to the single Yb 2+ -doped sample, the Eu 2+ -Yb 2+ codoped sample showed improved emission intensity, fluorescence lifetime, quantum efficiency, and thermal stability. An efficient energy transfer process from Eu 2+ ions to Yb 2+ ions was proposed to be responsible for the enhancement. The highest energy transfer efficiency was estimated to be 91.9%. A broadband yellow emission with full width at half maximum of ∼170 nm was also observed in the Eu 2+ -Yb 2+ codoped sample, which could be assigned to the co-excitation of Eu 2+ and Yb 2+ ions. In view of too low quantum efficiency and the considerable thermal quenching of the emission at the operation temperature of high-power LED (>1 W/mm 2 ), the SrSi 2 O 2 N 2 :Eu 2+ /Yb 2+ phosphor might be only potential for low-power high Ra pc-white LED.